Sheet metal combustion chamber, flame tube, and the like



Nov. 10, 1953 w. BONSALL 2,658,339

SHEET METAL COMBUSTION CHAMBER, FLAME TUBE, AND THE LIKE .Filed Nov. 9,1951 EB 0 5L Patented Nov. 10, 1953 SHEET METAL COMBUSTION CHAIVIBER,FLAME TUBE, AND THE LIKE William Bonsall, Burnley, England, assignor toJoseph Lucas Limited, Birmingham, England Application November 9, 1951,Serial No. 255,571

Claims priority, application Great Britain November 29, 1950 1 Claim. 1

This invention relates to an air-jacketed sheet metal combustionchamber, flame tube, or like body of the kind used in a jet engine, orgas turbine, or for other purposes, and in which hot gases are generatedor conveyed, the surface or surfaces of the body having therein holesfor the admission of air from the jacket.

One of the difliculties experienced when such a body is in use, is thecracking of the edges of the holes due to stresses set up in the metalby the heating action of the gases, or other causes, and the object ofthe present invention is to enable this difiiculty to be overcome in asimple manner.

The invention consists in forming in the metal around the holes,transverse corrugations adapted to allow free expansion and contractionof the metal at the edges of the holes.

In the accompanying drawing:

Figure 1 is a sectional side elevation of a combustion chamber or flametube having therein air-admission holes such as are required to beformed in accordance with the invention.

Figures 2 and 3 are respectively a plan and cross section illustratingto a larger scale than Figure 1, a hole shaped in accordance with theinvention, Figure 3 being taken on the line 33 of Figure 2.

The combustion chamber or flame tube a. shown in Figure 1 is of knownform, and is provided with holes as b of the same or different sizesthrough which air can flow into the chamber or tube from a surroundingair jacket c.

According to the invention, and as shown in Figures 2 and 3, the metalaround those holes whose edges are liable to crack, is subjected to theaction of press tools whereby a ring of transverse corrugations d isformed around each hole. These corrugations extend radially from thehole to any convenient and suitable extent, and they may be tapered inthe direction of their length, the maximum depth being .at the edge ofthe hole. The pitch and depth of the corrugations is made appropriate tothe diameter of the hole and thickness of the metal, but in all casesthey are such as will relieve the metal of the detrimental stresses.

Whilst for most purposes it is convenient to treat all the holes in themanner above described, this is not essential, as the treatment may beapplied only to the edges of those holes which in bodies of conventionalconstruction have been found to be susceptible to cracking.

By this invention, cracking of the edges of the holes can be obviated ina very simple manner.

Havin this described my invention what I claim as new and desire tosecure by Letters Patent is:

A sheet metal hot gas chamber of elongated form, and an air jacketsurrounding said chamber, said chamber being provided with a pluralityof holes through which air from said jacket is admissible to saidchamber, and the sheet metal around said holes being formed withcorrugations which extend radially from said holes and allow freeexpansion and contraction of the metal bounding said holes.

WILLIAM BONSALL.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,159,322 Livingston Nov. 2, 1915 1,581,488 Lewis Apr. 20,1926 2,477,583 DeZubay et al Aug. 2, 1949 2,513,325 Hundstad July 4,1950 2,543,755 Berger Mar. 6, 1951

